The invention relates to a spark-ignition rotary internal-combustion engine.
Among the many projects that have been presented for creating a new engine having improved characteristics with respect to the ones still presently in use, only a few have followed an innovative path which is entirely revolutionary with respect to current engines, which have now been available for over one hundred years.
In recent times, so-called rotary engines, or lobed engines and other engines of various kinds and functionalities, in which the operating cycles are similar to those of conventional engines, but in which the rod-and-crank system lacks, have been presented.
Merely as an example, mention is made of the Wankel engine, composed of two bodies arranged one inside the other so that the outer body is fixed and the inner one has a xe2x80x9cplanetaryxe2x80x9d motion which, at each rotation through 360xc2x0, generates variable-volume combustion chambers.
The invention consists in providing a rotary internal-combustion engine which has the same operating principles as reciprocating engines, of the two-stroke and four-stroke types, but has a rotary operation.
This aim is achieved with a rotary internal-combustion engine, characterized in that it uses a plurality of pistons having a reciprocating motion, each piston being able to slide within a cylinder in an identical spaced angular arrangement in a same circumference, where the cylinders are accommodated in appropriately provided seats formed in a rotating body or rotor which rotates coaxially inside a fixed body or stator, in which the inlet ducts for the air-fuel mix and the exhaust duct for the burnt gases are formed together with the seat for the spark-plug, as in conventional internal-combustion engines.
The surfaces between the rotor and the stator have minimal tolerances and are manufactured with a spherical surface so as to give perfect balancing to the interior of the system in rotary motion.
The rotor, which assumes the shape of a spherical sector with two flat faces, is supported by a fixed supporting shaft which is rigidly coupled to the body of the stator by using two lateral flanges which are freely keyed, by interposing bearings, on said fixed supporting shaft.
The reciprocating motion of the pistons is achieved by engaging them so that they follow over 360xc2x0 the profile of a fixed eccentric element having a circular cross-section by virtue of the coupling of connecting rods, in which the big end is freely inserted in said profile of the eccentric element while the small end is inserted in the pin of the piston, the axis of said eccentric element being offset and parallel to the axis of the engine, i.e., to the axis that constitutes simultaneously both the axis of said fixed supporting shaft and the rotation axis of the rotor, within which the pistons slide with a reciprocating motion, said pistons being four or six.
In this solution, the rotor operates by turning about its own axis; clearly, the inserted cylinders, by following this rotation, force the pistons to slide within their walls, said pistons being coupled by connecting rods which are connected to the eccentric element; this produces a reciprocating rectilinear motion and cyclically varies, with a 360xc2x0 period, the volume of the combustion chamber formed between the head of the piston and the head of the cylinder, constituted by the internal surface of the stator.
The eccentricity of the axis of the eccentric element with respect to the axis of the engine has such a value that it is possible to produce continuously, in each one of the combustion chambers that correspond to the pistons, a continuous variation of their volumes, thus ensuring an operation which is similar to the operation of a conventional internal-combustion engine of the four-stroke type (intake, compression, power, exhaust).
The device used by the piston to continuously follow the circular profile of the eccentric element has a connecting rod for each piston; said connecting rod is keyed at one end to said pin and at the other end to the eccentric surface, with a bearing or roller cage inserted.
The advantages of the operation of the two-stroke engine produced by the absence of the distribution mechanisms are achieved with the engine according to the invention by providing a distribution which is controlled by the rotor, during its 360xc2x0 rotation, which gradually opens and closes two ports formed in the body of the stator, i.e., an inlet port for the air-fuel mix and an exhaust port for the burnt gases.